It is completely natural to feel nervous before a job interview but you can minimize pre-interview jitters with some preparation. Hopefully you have completed initial research on the company you applied for before being called in for an interview but you are going to need to do more. You will never know exactly what is going to be asked of you (unless you have an inside source), but you can be ready for the questions by knowing your stuff.
Look up the company website and study the history, about us page, and the products and services that are offered. Even if you are pretty sure you are not going to be quizzed on how the company came to be, it will give you insight into how the company operates and their philosophy. By of these factors should influence how you answer your questions. If it is obvious they place high value on team players, you should brainstorm situations when you have displayed this trait.
If you are applying for a sales position, you can be prepared for any role playing questions because you have taken the time to learn the companys products and services. It will be impressive to your interviewer that you have taken the time to research the information. It shows a commitment to details and a true interest in the company.
Another way to prepare for an interview is to complete a practice run with a friend or family member. Have them ask you questions and answer them as if you were already in the interview, dont break character during the role play either. There are many questions that are asked in a typical interview (what are your strengths and weaknesses) dont let them come as a surprise to you practice so you can answer with confidence.
A potential employer wants to hire people with a positive attitude. You should project this image in your demeanor, facial expressions, and most importantly in the content of your answers. You may be the strongest candidate that the interviewer has seen but you still will not get the job if you are negative and insult former bosses or co-workers.
The best way to do this is to put a positive spin on all of your answers. Many interviews will include a question along one of these lines:
Have you had a challenging relationship with a co-worker or boss? Tell us about it. What conditions in a workplace make it hard to do your job? How can people tell when you are in a bad mood at work?
Really, all of these are trick questions. Yes, the interviewer really does want to know how you have handled conflict in the workplace and how you deal with a bad day at work. But, they want to see if you can explain this without talking negatively and show that you can problem solve your way out of certain situations. Even if you have a great story to tell about you and a co-worker, unless you handled yourself as professionally as possible and the story portrays you in a positive light do not tell it.
If an interviewer asks how co-workers or customers can tell if you are in a bad mood, there is only one right answer, They cant. You can (and should) elaborate on this, but by answering the question in this vein you are showing that you can leave personal problems and stresses outside the workplace without them affecting your job or others.
Be the kind of person that people want to hire, realistic with an attitude of getting along with others and the ability to get a job done.